The complete DNA sequence of the double-stranded DNA restriction fragment containing the two tandem promoters which begin late transcription of the T7 genome by T7 RNA polymerase will be completed. The mRNA produced from this fragment by the T7 enzyme contains the RNA'se III processing site between genes 1 and 1.1. We intend to use this small complete transcriptional unit to study the molecular details of promoter-polymerase interaction by spectroscopic and chemical modification methods, as well as pursue enzymological studies of the mechanism of transcription. Studies of the structure of the homogeneous T7 RNA polymerase are also underway. Multinuclear NMR (1H, 31P and 19F) methods are being used to probe the structure of bacteriophage T4 with oligodeoxynucleotides of defined sequence. The role of phosphorylation-dephosphorylation in the structure and function of non-histone chromosomal proteins is under investigation.